Bicep deploy - allow user to specify mode

Add support to let the user specify the deployment mode similar to https://docs.microsoft.com/en-us/cli/azure/deployment/group?view=azure-cli-latest#az-deployment-group-create

For some context, deployment mode could be incremental or complete. We currently support default mode, which is incremental. The difference is how existing resources in the resource group are handled that aren't in the template.

Short description:
1. Complete - resources that exist in the resource group but aren't specified in the template are deleted
2. Incremental - resources that exist in the resource group but aren't specified in the template are left unchanged. Resources in the template are added to the resource group

For more details see https://docs.microsoft.com/en-us/azure/azure-resource-manager/templates/deployment-modes

cc: @ucheNkadiCode